The new Plan to which the order is to be upgraded/downgraded. To fetch the Plan details i.e. plan-id etc, use this method.

Note

The new Plan category can be websitebuilder_plan or email_plan.

The new Plan category can be linux_hosting_plan only if the current Plan category is linux_hosting_plan. Similarly, the new Plan category can be windows_hosting_plan only if the current Plan category is windows_hosting_plan. In all other cases, an exception will be thrown if the new Plan category is linux_hosting_plan or windows_hosting_plan.